It is known that skin conductance of a user is related with the level of arousal of the user. Everything that emotionally touches the user activates the sweat glands in the skin, leading to a better conductor path through the skin. For example, in a known lie detector or polygraph, a skin conductance sensor connected to the palm of the hand or the fingers is used.
However, the skin conductance can also be measured on other parts of the body of the user. Indeed, in many locations the skin conductance could be measured, even though with a less fine structure and at a lower signal-to-noise ratio. For example, skin conductance can be measured on the wrist of the user using a (skin conductance) wristband.
Using a skin conductance wristband is different from the traditional skin conductance measurement methods in that the period of measurement can be much longer. It may extend over several weeks. This requires the use of an interface between wristband and skin that causes no problems to the user wearing the wristband, such as skin irritation or skin coloration.
US 2010/0268056 A1 discloses a flexible wrist/hand band with a sensor to detect electrodermal activity (EDA). The circuitry for the EDA sensor fits, and is secured within a hydrophobic pouch on the band. A hydrophobic, breathable material is used to form the pouch for circuitry, and to form parts of the wearable band. The electrodes are hosted by a flexible, breathable material. In some embodiments, the material used for this flexible, breathable material may be the same as the breathable, hydrophobic material used to form the pouch. The wrist is not a standard location for measuring EDA since the sweat glands there tend to be less sensitive than those on the palm of fingers, where EDA is traditionally measured. This issue, coupled with the use of dry electrodes, means that it usually takes at least 15 minutes (depending on humidity and the individual's temperature) before the moisture built up between the skin and electrodes is sufficient to show a range of responsiveness on the wrist.
A problem with such a wristband can be that for a certain percentage of users, the skin conductance measurement signal is too low to register. Thus, for some users a very poor or no skin conductance measurement at all may be obtained.